The invention is concerned with homopolar dynamoelectric machines with generally cylindrical clearances between the stator and rotor.
In conventional machines of this type, the armature current circulates in the bulky ferromagnetic material of the stator and the rotor. This creates an undesired orthoradial-magnetic field which becomes superimposed upon the two axial and radial components of the magnetic excitation vector created at all points of the stator and rotor by the induction windings of the device. The armature current in this type of machine may be several tens of thousands of amperes, and produces an armature-reaction magnetic field which is perpendicular and generally is from twenty to one hundred times more intense than the inductive magnetic field. This results in a magentic saturation of the material in a nearly orthoradial resultant direction, producing a considerable diminishment of the useful component of the magnetic induction, and considerably limiting the performance of the machine under load.